The person or team who had the best utilization of such a simple app would be awarded $2,500 at the end of this week. Some teams, Liao told us, are using the app to "yo" when you make breakfast or "yo" when you want to play a basketball game.

But this group of friends wanted to do something useful. The team created the username "YoTheWorld" in order to collect "Yo's for good."

In an email to Business Insider, Liao says,

If YOTHEWORLD gets the most Yo's by July 4th, 11:59pm PST and wins the $2500 prize, we will donate all of the money to a girl named Malaika. She's a four year-old girl from Haiti with atrioventricular canal defect. This means that blood flows through her heart abnormally. If she doesn't get surgery soon for it, her condition may turn fatal.

This is Malaika.

YoTheWorld And helping her is super easy. All you have to do is download "Yo" from the app store and add YOTHEWORLD to your friends list.

So far the team has received a little under 2,000 Yo's to YoTheWorld.

Business Insider

"We're not saying that the other teams aren't doing cool things, but if they win, they're pocketing the $2500," Liao explained in an email. "We don't need the money but Malaika does."